Optical pickup lens, molded optical component, handling method, and mold for optical component

ABSTRACT

An objective lens for use in an optical pickup apparatus for conducting recording and/or reproducing information for an optical information recording medium, has a lens section shaped in an approximate circle and including a flange section; and a connecting section integrally provided to the lens section. The objective lens satisfies the following conditional formulas:  
     0.5≦A≦2.0, 0.3A≦B≦1.7A  
     where A is a diameter of the lens section when the lens section is viewed from an direction of an optical axis, and B is a width of the connecting section when the connecting section is viewed from the direction of the optical axis.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a pickup lens for an opticaldisk which is used for reading information from a storage medium, orrecording, mainly by using a laser beam, and in particular, to a pickuplens for an extremely small optical disk.

[0002] There are various formats (specifications) for informationrecording media available on the market, and various technologies areemployed and studied for the various formats.

[0003] In recent years, in particular, a broadband has become popular tocreate a broadband age, and there are circulating high-volume contentsof images, animations and sounds. It is therefore necessary, even forgeneral users, to stock high-volume data.

[0004] With respect to a recording medium for data stocking, originalones were those wherein audio cassette tapes were used, and FD (floppydisk) is still used even today. In recent years, Zip (high-volume floppydisk having the measure of capacity of 100 M-200 M), MO(photo-electro-magnetic disk having the measure of capacity of 640 M-2.3G), CD (optical disk having the measure of capacity of 640-700 M) andDVD (optical disk having the measure of capacity of 4.7 G) are used,which shows that the measure of capacity has grown great.

[0005] Among the aforesaid recording media, those utilizing light havetheir own optical systems.

[0006] The optical disks mentioned above have started from the music CD,and therefore, it is always necessary for the DVD which is becoming aleading recording medium now to consider interchangeability with CD, anda size of the DVD is large, which makes it difficult to provide asmall-sized equipment, resulting in a problem. To solve this problem, asmall-sized medium in a size of 8 cm and a deformed medium having a sizeof a business card have made an appearance, but it is unavoidable thatthey have less capacity.

[0007] Further, the DVD has a problem that many standards concerninginformation recording are present and interchangeability between them isinsufficient.

[0008] With respect to the photo-electro-magnetic disk, problems ofinterchangeability with standards for low volume and problems that asize of a medium restricts a size of equipment remain unchanged,although the measure of capacity has been made great.

[0009] For those problems, there has been proposed a standard concerninga small-sized recording medium which is quite novel.

[0010] However, when a medium is small in size, an optical pickup lensand a unit are required to be small in size.

[0011] When an optical pickup lens and a unit are made to be small insize, manufacturing, assembling and adjustment of the lens itself becomeextremely difficult.

SUMMARY OF THE INVENTION

[0012] An object of the invention, therefore, is to propose forms whichmake manufacturing, assembling and adjustment to be easy for an opticalpickup lens and an optical pickup unit which are extremely small.

[0013] The above object can be attained by the following structures andmethods in respective Item.

[0014] Item (1-1)

[0015] An objective lens used in an optical pickup device that conductsrecording and/or reproduction of information for an optical informationrecording medium,

[0016] wherein there are provided

[0017] a lens section which includes a flange section and is almost in acircular form, and a connecting section used as a supporting section forthe lens section, the connecting section is provided to be solid withthe lens section, and each of them satisfies the following relations;

0.5≦A≦2.0

0.3A≦B≦1.7A

[0018] where A represents a diameter (mm) of the lens section viewed inthe optical axis direction, and B represents a width (mm) of theconnecting section viewed in the optical axis direction.

[0019] Item (1-2)

[0020] The objective lens according to Item (1-1), wherein a connectingsection is provided to be extended from the lens section.

[0021] Item (1-3)

[0022] The objective lens according to Item (1-2), wherein the objectivelens is formed by filling resins through a single inlet in a metal mold.

[0023] Item (1-4)

[0024] The objective lens described in Item (1-2) or in Item (1-3),wherein the following expression is satisfied.

0.3A≦B≦0.8A

[0025] Item (1-5)

[0026] The objective lens described in Items (1-2)-(1-4), wherein theconnecting section is cut so that nothing may be protruded outside ashape which is roughly circular when viewed in the direction of anoptical axis.

[0027] Item (1-6)

[0028] The objective lens according to Item (1-1), wherein twoconnecting sections are provided to be extended from the lens section inthe direction to face each other.

[0029] Item (1-7)

[0030] The objective lens according to Item (1-6), wherein the twoconnecting sections are different from each other.

[0031] Item (1-8)

[0032] The objective lens according to Item (1-7), wherein the twoconnecting sections are different from each other in terms of thicknessin the optical axis direction.

[0033] Item (1-9)

[0034] The objective lens according to Item (1-6)-Item (1-8), whereinthe two connecting sections are different from each other in terms ofthickness in the direction perpendicular to the optical axis.

[0035] Item (1-10)

[0036] The objective lens according to Item (1-6)-Item (1-9), whereinthe two connecting sections are different from each other in terms of alength of the width viewed in the direction of the optical axis.

[0037] Item (1-11)

[0038] The objective lens according to Item (1-1), wherein a lenssection is formed to be arranged at the center of a rectangularconnecting section.

[0039] Item (1-12)

[0040] The objective lens according to Item (1-6)-Item (1-11), whereinthe objective lens is formed by filling resins through a single orplural inlets in a metal mold.

[0041] Item (1-13)

[0042] The objective lens according to Item (1-6)-Item (1-10) or to Item(1-12), wherein two connecting sections are provided to be extended fromthe lens section in the direction to face each other, and are formedwith resins filled through an edge portion of each connecting section.

[0043] Item (1-14)

[0044] The objective lens according to Item (1-11) or Item (1-12),wherein a lens section is formed to be arranged at the center of arectangular connecting section, and resins are filled through an edgeportion of the connecting section to be formed.

[0045] Item (1-15)

[0046] The objective lens according to Item (1-12)-Item (1-14), whereina weld is located outside an optical functional surface of the lenssection.

[0047] Item (1-16)

[0048] The objective lens according to Item (1-1)-Item (1-15), whereinthe objective lens is an aspherical lens.

[0049] Item (1-17)

[0050] The objective lens according to Item (1-1)-Item (1-16), whereinthe objective lens is a lens obtained through compression molding.

[0051] Item (1-18)

[0052] The objective lens according to Item (1-1)-Item (1-16), whereinthe objective lens is a lens obtained through injection molding.

[0053] Item (1-19)

[0054] The objective lens according to Item (1-18), wherein theconnecting section serves also as a resin inflow path for the lenssection.

[0055] Item (1-20)

[0056] The objective lens according to Item (1-18)-Item (1-19), whereinthe objective lens is a plastic lens.

[0057] Item (1-21)

[0058] The objective lens according to Item (1-17), wherein theobjective lens is a glass lens.

[0059] Item (1-22)

[0060] The objective lens according to Item (1-1)-Item (1-21), wherein adiffractive Item is formed on the optical functional surface of theobjective lens.

[0061] Item (1-23)

[0062] A manufacturing method for an optical element for forming byfilling resins through a plurality of inlets in a metal mold, whereinthe time to start injecting resins is staggered when filling resinsthrough the plural inlets.

[0063] Inventions relating to a handling method among the presentinventions are attained by the following Items.

[0064] Item (2-1)

[0065] An optical molded component having therein a supporting shaftsection having a first cross-sectional area, a connecting section thatis provided to be continued in the axial direction of the supportingshaft section and has a cross-sectional area smaller than the firstcross-sectional area and an optical functional section provided to becontinued from the connecting section, wherein the total weight of thesupporting shaft section and the connecting section is greater than theweight of the optical functional section.

[0066] Item (2-2)

[0067] An optical molded component having therein a supporting shaftsection having a first cross-sectional area, a connecting section thatis provided to be continued in the axial direction of the supportingshaft section and has a cross-sectional area smaller than the firstcross-sectional area and an optical functional section provided to becontinued from the connecting section, wherein the total weight of thesupporting shaft section and the connecting section is not less than 70%of the whole weight.

[0068] Item (2-3)

[0069] An optical molded component having therein a supporting shaftsection having a first cross-sectional area, a connecting section thatis provided to be continued in the axial direction of the supportingshaft section and has a cross-sectional area smaller than the firstcross-sectional area and an optical functional section provided to becontinued from the connecting section, wherein an information recordingsite is provided on the supporting shaft section.

[0070] Item (2-4)

[0071] An optical molded component having therein a supporting shaftsection having a first cross-sectional area, a connecting section thatis provided to be continued in the axial direction of the supportingshaft section and has a cross-sectional area smaller than the firstcross-sectional area and an optical functional section provided to becontinued from the connecting section, wherein an information recordingsite is provided on the connecting section.

[0072] Item (2-5)

[0073] The optical molded component described in Item (2-1)-Item (2-4),wherein a shape of a section of the supporting shaft section is almostcircular.

[0074] Item (2-6)

[0075] The optical molded component described in Item (2-1)-Item (2-5),wherein a shape of a section of the supporting shaft section is almosttrapezoid.

[0076] Item (2-7)

[0077] The optical molded component described in Item (2-1)-Item (2-6),wherein a shape of a section of the supporting shaft section is almostsemicircular.

[0078] Item (2-8)

[0079] In the invention described in Item (2-8), it is characterizedthat a parallel flat portion that is almost in parallel with a chordsection is formed on a part of an arc section of the supporting sectionin the optical molded component described in Item (2-7).

[0080] Item (2-9)

[0081] In the invention described in Item (2-9), it is characterizedthat a protruded portion that is protruded from the parallel flatportion stated above and is in a shape which is almost a truncatedsquare pyramid is formed in the optical molded component described inItem (2-8).

[0082] Item (2-10)

[0083] In the invention described in Item (2-10), it is characterizedthat a side section of the protruded portion is composed of a pair oflongitudinal sides which face each other in the longitudinal directionof the supporting section and a pair of lateral sides which face eachother in the lateral direction, and an angle formed between thelongitudinal side and the parallel flat section is made to be 45° orless, in the optical molded component described in Item (2-9).

[0084] Item (2-11)

[0085] The optical molded component described in Item (2-7) to Item(2-10), wherein a normal line on a chord section of the approximatesemicircle almost agrees with an optical axis on an optical functionalsurface of the optical functional section.

[0086] Item (2-12)

[0087] The optical molded component described in Item (2-1)-Item (2-11),wherein a protruded portion is formed on the supporting shaft section.

[0088] Item (2-13)

[0089] In the invention described in Item (2-13), it is characterizedthat the protruded portion is formed to be almost in a truncated squarepyramid, in the optical molded component described in Item (2-12).

[0090] Item (2-14)

[0091] In the invention described in Item (2-14), it is characterizedthat a corner section of the convex portion is chamfered, in the opticalmolded component described in Item (2-13).

[0092] Item (2-15)

[0093] The optical molded component described in Item (2-1)-Item (2-14),wherein a concave portion is formed on the supporting shaft section.

[0094] Item (2-16)

[0095] The optical molded component described in Item (2-1) Item (2-15),wherein a stress-concentration portion is formed on the connectingsection.

[0096] Item (2-17)

[0097] The optical molded component described in Item (2-16), whereinthe stress-concentration portion is a V-shaped concave portion which isconcave in the direction which is mostly perpendicular to the opticalaxis on the optical functional surface of the optical functionalsection.

[0098] Item (2-18)

[0099] The optical molded component described in Item (2-16), whereinthe stress-concentration portion is a V-shaped concave portion which isconcave in the direction which is mostly the same as the optical axis onthe optical functional surface of the optical functional section.

[0100] Item (2-19)

[0101] In the invention described in Item (2-19), it is characterizedthat the connecting section has an index portion that is based on adistance from the center of an optical axis of the optical functionalsection, in the optical molded component described in either one ofItems (2-1)-(2-18).

[0102] Item (2-20)

[0103] In the invention described in Item (2-20), it is characterizedthat the index portion is formed by cutting into the connecting section,in the optical molded component described in Item (2-19).

[0104] Item (2-21)

[0105] In the invention described in Item (2-21), it is characterizedthat the index portion is formed to be protruded from the connectingsection, in the optical molded component described in Item (2-19).

[0106] Item (2-22)

[0107] In the invention described in Item (2-22), it is characterizedthat the index portion is formed to be a straight line extending in thelateral direction of the connecting section, in the optical moldedcomponent described in either one of Items (2-19)-(2-21).

[0108] Item (2-23)

[0109] In the invention described in Item (2-23), it is characterizedthat the index portion is formed to be a locus of a circle having aprescribed radius whose center is on the optical axis in the opticalmolded component described in either one of Items (2-19)-(2-21).

[0110] Item (2-24)

[0111] When handling the optical molded component described in Item(2-19 to (2-23), a method of handling an molded optical component ischaracterized in that an optical molded component is taken out of ametal mold for molding an optical molded component that is provided witha first resin inflow path having a first cross-sectional area, a secondresin inflow path being located ahead of the first resin inflow path inthe direction of resin flow and having a cross-sectional area smallerthan the first cross-sectional area and an optical functional sectionmolding section being located further ahead of the second resin inflowpath in the direction of resin flow, and then, the optical moldedcomponent is handled on the basis of a site formed by the first resininflow path.

[0112] Item (2-25)

[0113] When handling the optical molded component described in Item(2-19 to (2-23), a method of handling an molded optical component ischaracterized in that an optical molded component is taken out of ametal mold for molding an optical molded component that is provided witha first resin inflow path having a first cross-sectional area, a secondresin inflow path being located ahead of the first resin inflow path inthe direction of resin flow and having a cross-sectional area smallerthan the first cross-sectional area and an optical functional sectionmolding section being located further ahead of the second resin inflowpath in the direction of resin flow, and then, the optical moldedcomponent is handled on the basis of a site which is formed by the firstresin inflow path and is continued to a site formed by the second resininflow path, after the site formed by the first resin inflow path iscut.

[0114] Item (2-26)

[0115] When handling the optical molded component described in Item(2-19 to (2-23), a method of handling an molded optical component ischaracterized in that an optical molded component is taken out of ametal mold for molding an optical molded component that is provided witha first resin inflow path having a first cross-sectional area, a secondresin inflow path being located ahead of the first resin inflow path inthe direction of resin flow and having a cross-sectional area smallerthan the first cross-sectional area and an optical functional sectionmolding section being located further ahead of the second resin inflowpath in the direction of resin flow, and then, the optical moldedcomponent is handled on the basis of a site which is formed by the firstresin inflow path and is continued to a site formed by the second resininflow path, after the prescribed site formed by the first resin inflowpath is cut.

[0116] Item (2-27)

[0117] The method of handling an optical molded component described inItem (2-26), wherein the aforementioned prescribed site is a site formedby the first resin inflow path mentioned above that is away, by adistance determined in advance, from a boundary between the site formedby the first resin inflow path and the site formed by the second resininflow path.

[0118] Item (2-28)

[0119] The method of handling an optical molded component described inItem (2-24)-Item (2-27), wherein “handling” means positioning of theoptical molded component.

[0120] Item (2-29)

[0121] The method of handling an optical molded component described inItem (2-24)-Item (2-28), wherein “handling” means holding of the opticalmolded component.

[0122] Item (2-30)

[0123] The method of handling an optical molded component described inItem (2-24)-Item (2-29), wherein “handling” means mounting of theoptical molded component.

[0124] Item (2-31)

[0125] The method of handling an optical molded component described inItem (2-24)-Item (2-30), wherein “handling” means cutting of the opticalmolded component.

[0126] Item (2-32)

[0127] The method of handling an optical molded component described inItem (2-24)-Item (2-31), wherein “handling” means cutting of the siteformed by the second resin inflow path after combining the opticalfunctional section of the optical molded component with another member.

[0128] Item (2-33)

[0129] The method of handling an optical molded component described inItem (2-32), wherein another member stated above is a cartridge forconveyance.

[0130] Item (2-34)

[0131] The method of handling an optical molded component described inItem (2-32), wherein another member stated above is a pickup unit.

[0132] Item (2-35)

[0133] The method of handling an optical molded component described inItem (2-24)-Item (2-34), wherein “handling” means recording informationon the site formed by the first resin inflow path.

[0134] Item (2-36)

[0135] In the invention described in Item (2-36), it is characterizedthat the “handling” is to record information on a portion formed by thesecond resin inflow path in the optical molded component, in the methodof handling an optical molded component described in either one of Item(2-24)-(2-34).

[0136] Item (2-37)

[0137] The method of handling an optical molded component described inItem (2-35) or (2-36), wherein the information means a number of a metalmold.

[0138] Item (2-38)

[0139] The method of handling an optical molded component described inItem (2-35)-Item (2-37), wherein the information means a cavity number.

[0140] Item (2-39)

[0141] The method of handling an optical molded component described inItem (2-35)-Item (2-38), wherein the recording of information isconducted by marking.

[0142] Item (2-40)

[0143] The method of handling an optical molded component described inItem (2-35)-Item (2-39), wherein the recording of information isconducted by printing.

[0144] Item (2-41)

[0145] The method of handling an optical molded component described inItem (2-35)-Item (2-40), wherein the recording of information isconducted by pasting.

[0146] The invention of the handling method relating to the moldedcomponent among the present inventions can be attained by the followingmeans.

[0147] Item (2-42)

[0148] The method of handling an optical molded component described inItem (2-12)-Item (2-15), wherein the protruded portion and/or theconcave portion is used as an index for positioning.

[0149] Item (2-43)

[0150] The method of handling an optical molded component described inItem (2-12)-Item (2-15), wherein the protruded portion and/or theconcave portion is used as a guide in the course of handling.

[0151] Item (2-44)

[0152] A metal mold for molding an optical molded component described inany one of Items (2-1) to (2-23), having therein a first resin inflowpath having a first cross-sectional area, a second resin inflow pathbeing located ahead of the first resin inflow path in the direction ofresin flow and having a cross-sectional area smaller than the firstcross-sectional area and an optical functional section molding sectionbeing located further ahead of the second resin inflow path in thedirection of resin flow, wherein there is formed an optical moldedcomponent having therein a supporting shaft section formed by the firstresin inflow path, a connecting section formed by the second resininflow path and an optical functional section formed by the opticalfunctional section molding section.

[0153] Item (2-45)

[0154] The metal mold for molding an optical molded component describedin Item (2-44), wherein a part of the first resin inflow path is formedso that a three-dimensional distinguishing mark may be formed.

[0155] Item (2-46)

[0156] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-45), wherein the direction of resin flow for eachof the first resin inflow path and the second resin inflow path isalmost linear.

[0157] Item (2-47)

[0158] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-46), wherein the direction of resin flow for thefirst resin inflow path and that for the second resin inflow path are inaccord with each other, and are mostly linear.

[0159] Item (2-48)

[0160] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-47), wherein the direction of resin flow for thefirst resin inflow path and that for the second resin inflow path are inthe relationship to cross mostly at right angles.

[0161] Item (2-49)

[0162] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-48), wherein the first resin inflow path is arunner.

[0163] Item (2-50)

[0164] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-49), wherein the second resin inflow path is agate.

[0165] Item (2-51)

[0166] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-50), wherein the first resin inflow path isformed so that a shape of a section of the supporting shaft section maybe almost circular.

[0167] Item (2-52)

[0168] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-50), wherein the first resin inflow path isformed so that a shape of a section of the supporting shaft section maybe almost trapezoid.

[0169] Item (2-53)

[0170] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-50), wherein the first resin inflow path isformed so that a shape of a section of the supporting shaft section maybe almost semicircular.

[0171] Item (2-54)

[0172] The metal mold for molding an optical molded component describedin Item (2-53), wherein the first resin inflow path and the opticalfunctional section molding section are formed so that a normal line on achord section of the approximate semicircle may almost agree with anoptical axis on an optical functional surface of the optical functionalsection.

[0173] Item (2-55)

[0174] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-54), wherein the first resin inflow path isformed so that a protruded portion may be formed on the supporting shaftsection.

[0175] Item (2-56)

[0176] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-55), wherein the first resin inflow path isformed so that a concave portion may be formed on the supporting shaftsection.

[0177] Item (2-57)

[0178] The metal mold for molding an optical molded component describedin Item (2-44)-Item (2-56), wherein the second resin inflow path isformed so that a stress-concentration portion may be formed on theconnecting section.

[0179] The invention relating to the method of molding employing a metalmold among the present inventions can be attained by the followingmeans.

[0180] Item (2-58)

[0181] An optical molded component that is molded by the metal mold formolding an optical molded component in the aforesaid Items(2-44)-(2-57), and has a supporting shaft section formed by the firstresin inflow path, a connecting section formed by the second resininflow path and the optical functional section formed by the opticalfunctional section molding section.

[0182] The invention relating to the method of molding employing a metalmold among the present inventions can be attained by the followingmeans.

[0183] Item (2-59)

[0184] A method of molding an optical molding component that molds anoptical molded component by the use of the metal mold for molding anoptical molded component in the aforesaid Items (2-44)-(2-57).

[0185] Item (2-60)

[0186] In the invention described in Item (2-60), it is characterizedthat the optical molded component described in either one of Items(2-1)-(2-23) is provided in the optical pickup unit.

[0187] The invention relating to a method of assembling an opticalpickup unit among the present inventions can be attained by thefollowing means.

[0188] Item (2-61)

[0189] An optical pickup unit assembling method for the optical pickupunit described in Item (2-60) wherein a molded component in which anoptical functional section and a supporting shaft section that isgreater than the optical functional section are formed integrallythrough a connecting section is incorporated with an optical pickup unitthrough the optical functional section while holding the supportingshaft section, and then, the connecting section is cut.

[0190] Item (2-62)

[0191] An optical pickup unit assembling method for the optical pickupunit described in Item (2-60) wherein a molded component in which anoptical functional section and a supporting shaft section that isgreater than the optical functional section are formed integrallythrough a connecting section is incorporated with a housing containerthrough the optical functional section while holding the supportingshaft section, and then, the connecting section is cut.

[0192] Item (2-63)

[0193] The optical pickup unit assembling method described in Item(2-61)-Item (2-62), wherein the supporting shaft portion is greater thanthe optical functional section in terms of volume.

[0194] Item (2-64)

[0195] The optical pickup unit assembling method described in Item(2-61)-Item (2-63), wherein the supporting shaft portion is greater thanthe optical functional section in terms of weight.

BRIEF DESCRIPTION OF THE DRAWINGS

[0196]FIG. 1 is a diagram of an objective lens relating to Example 1that is viewed in the direction of an optical axis.

[0197]FIG. 2 is a diagram of the objective lens shown in FIG. 1 that isviewed in the direction shown with “a”.

[0198]FIG. 3 is a diagram of an objective lens relating to Example 2that is viewed in the direction of an optical axis.

[0199]FIG. 4 is a diagram of the objective lens shown in FIG. 3 that isviewed in the direction shown with “a”.

[0200]FIG. 5 is an example of an objective lens relating to Example 2.

[0201]FIG. 6 is an example of an objective lens relating to Example 2.

[0202]FIG. 7 is an example of an objective lens relating to Example 2.

[0203]FIG. 8 is a diagram of an objective lens relating to Example 3that is viewed in the direction of an optical axis.

[0204]FIG. 9 is a diagram of the objective lens shown in FIG. 8 that isviewed in the direction shown with “a”.

[0205]FIG. 10 shows a schematic view of the metal mold relating to theinvention.

[0206]FIG. 11 is an enlarged drawing of primary portions of the metalmold relating to the invention.

[0207]FIG. 12 is a perspective view of the molded component relating tothe invention.

[0208] FIGS. 13(a) to 13(g) each is a sectional view of the moldedcomponent relating to the invention.

[0209]FIG. 14 is a perspective view in the state where information isgiven to the supporting shaft section of the molded component relatingto the invention.

[0210] FIGS. 15(a) to 15(d) each is a sectional view of an examplewherein a three-dimensional distinguishing mark is provided on thesupporting shaft portion of the molded component relating to theinvention.

[0211] FIGS. 16(a) to 16(g) each is a perspective view of an examplewherein a three-dimensional distinguishing mark is provided on thesupporting shaft portion of the molded component relating to theinvention.

[0212]FIG. 17 is a sectional view of a metal mold wherein athree-dimensional distinguishing mark is provided on the supportingshaft portion of the molded component relating to the invention.

[0213] FIGS. 18(a) to 18(d) each is an enlarged drawing of primaryportions of the example wherein a stress-concentration portion isprovided on the connecting section of the molded component relating tothe invention.

[0214] FIGS. 19(a) and 19(b) each is a perspective view of an examplewherein an information recording site is provided on the supportingshaft portion of the molded component relating to the invention.

[0215] FIGS. 20(a) and 20(b) each is a perspective view of an example ofthe molded component relating to the invention.

[0216] FIGS. 21(a) and 21(b) each is a perspective view of an example ofthe molded component relating to the invention.

[0217]FIG. 22 is a sectional view explaining the separation of anoptical molded component from a mold.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0218] The contents of the invention will be explained in detail asfollows based on the drawings, to which, however, embodiments of theinvention are not limited.

EXAMPLE 1

[0219]FIG. 1 is a diagram showing objective lens 1 in Example 1 viewedin the optical axis direction, and FIG. 2 is a sectional view showingthe same objective lens viewed in the direction shown by the arrow (X).

[0220] The objective lens 1 is an objective lens made of plasticobtained by injection-molding resins filled in a metal mold.

[0221] Lens section 10 is composed of lens (optical functional surface)11 having an optical function and of a flange section provided tosurround the lens 11, and diameter A of the lens section 10 is 1.3 mm,while, the width of connecting section 20 is 1.2 mm. In the presentexample, B is equal to 0.92A, while, the conditions in Item (1-1) aresatisfied, and the shape in Item (1-2) is kept.

[0222] Therefore, handling and incorporating in a pickup device are easyin spite of an extremely small lens, because a connecting section isprovided for handling and for supporting the lens section, which is amerit. That is, the connecting section is used as a supporting sectionfor the lens section. It is further possible to give a product name, alot number and a metal mold number by conducting some printing andmarking or other on the connecting section.

[0223] It is also possible to structure so that no flange section may beprovided, however, it is preferable to provide a flange whenpositioning, handling, an influence on the lens surface and protectionof the lens surface are taken into consideration.

[0224] The plastic lens which is injection-molded as stated aboveemploys technologies in Item (1-18) and Item (1-19). Therefore, it ispossible to manufacture a large number of lenses in the same shapestably and at high speed. In particular, the plastic lens has anadvantage that inflow of resins and moldability are excellent becausedimensional conditions stipulated in Item (1-1) are satisfied.

[0225] Further, a shape of the metal mold is formed so that resins mayflow in from connecting section 20, and technologies in Item (1-3) andItem (1-18) are employed. Due to this, the shape and structure of themetal mold are not complicated, and a resin inflow path can be used as aconstitutional component.

[0226] The lens section 10 is arranged so that it may be positioned whenits flange section comes in contact with an unillustrated component onthe part of a pickup device when the lens section 10 is incorporated inthe pickup device, and NA is further stipulated as occasion demands onthe optical functional surface of lens surface 11.

[0227] In the objective lens 1, technologies of Item (1-16) are employedfor improving light-converging power, and the optical functional surfacethereof is formed to be in a shape of an aspheric surface.

[0228] Further, for the purpose of temperature compensation (improvementof temperature characteristics), a diffractive structure is formed onthe optical functional surface to be in a form of ring shaped zones bythe use of technologies of Item (1-22). The diffracting surface may beprovided either on the whole optical functional surface or on thedesired locations at need. It is further possible to provide thediffracting surface not only for the temperature compensation but alsofor improvement of optical characteristics and for opticalcharacteristics to be given, including correction of variousaberrations.

[0229] When no diffracting surface is required in particular, opticalfunctions may also be attained by a refracting interface only withoutproviding the diffracting surface.

[0230] Incidentally, though the total length C including a lens sectionand a width section is 3 mm, maximum thickness D (axial thickness inthis case) of the lens section is 0.41 mm and thickness E of theconnecting section is 0.2 mm in the foregoing, these figures may furtherbe selected suitably to be preferable.

[0231] As a comparison, a lens with a general view shown in FIG. 1wherein a diameter of a lens section and a width of a connecting sectionare made to be different in terms of dimension was prepared to bestudied. With respect to a size of the lens section first, when the sizewas smaller than that stipulated in the invention, insufficient quantityof light was caused, and sufficient optical efficiency was not attained.In addition, handling properties were lowered and assembling propertieswere worsened. Further, inflow of resins in the metal mold was worsened,and a yield for injection molding was lowered. When the size was greaterthan that stipulated in the invention, on the contrary, the lens wascloser to an objective lens for CD or DVD available presently on themarket, and it was difficult to downsize a recording medium and a pickupdevice, although optical characteristics were able to be attained. Whenthe size of the connecting section was smaller than that stipulated inthe invention, the resin inflow path was narrowed and resins did notflow in sufficiently, making injection molding itself to be impossible.When the connecting section was greater than that stipulated in theinvention, on the contrary, a shrinkage cavity (defectively moldedportion to which no resins flowed in) was caused on the connectingsection, which also made it impossible to conduct excellent injectionmolding.

[0232] In comparison with lenses stated above, the objective lens thatwas made to be within a range stipulated by the invention proved to beexcellent in terms of moldability and handling property and to be of noproblem in optical efficiency after the objective lens was incorporatedin a pickup device.

EXAMPLE 2

[0233] A general view shown in FIG. 3 represents a diagram of objectivelens 2 made of plastic in Example 2 that is viewed in the direction ofthe optical axis, and FIG. 4 is a sectional view of the same objectivelens viewed in the direction shown by the arrow (a), in which thetechnology of Item (1-4) is employed.

[0234] A point of difference between Example 1 and Example 2 is thatsecond connecting section 21 is further provided in Example 2, and otherpoints are the same as those in Example 1. Therefore, the same symbolsare given to the same structure, and explanation therefore will beomitted.

[0235] Due to the two connecting sections provided, there are advantagesthat handling property is improved by holding both connecting sectionsand that an area where marking and printing can be conducted isincreased.

[0236] Regarding these two connecting sections, it is either possiblethat at least one of 20 and 21 serves also as a resin inflow path asmentioned in Item (1-3) or Item (1-18), or possible that each of themserves also as a resin inflow path as mentioned in Item (1-11) and Item(1-12).

[0237] When both of the connecting sections are resin inflow paths, itis possible to form at high speed and surely because resins flow in athigh speed, and to prevent occurrence of a shrinkage cavity. Further,the time required for injection molding can be reduced, and a cycle timeis shortened, improving production efficiency.

[0238] Even when resins are made to flow in from the connecting sectionon one side, it is possible to form without any problem, provided thatthe dimensional conditions stipulated by the invention are satisfied.

[0239] Next, there will be explained an embodiment wherein a shape ofconnecting section 20 is different from that of connecting section 21.

[0240] When resins flow in from both of two connecting sections, resinswhich are unequal in terms of conditions meet in a metal mold, and aweld is naturally caused. If this weld interferes an optical functionalsurface of the lens section, optical functions themselves are affected,including a fall of transmittance and extension of errors in asphericalshapes. Therefore, it is necessary to devise proper arrangement.

[0241] As a method of solution from the aspect of a shape, it is aneffective technology to make the connecting sections to be different interms of size as shown in Item (1-5)-Item (1-10). As a practical methodto make connecting sections to be different in terms of size, it ispossible to employ a method to change a thickness in the direction of anoptical axis, a method to change a length in the direction perpendicularto an optical axis and a method to change a length of a width viewed inthe direction of an optical axis, by selecting properly or by combiningthem. To be concrete, shapes shown in FIGS. 5, 6 and 7 are conceivable.When a length of a width of the connecting section is made to bedifferent, in particular, the length is required to be within theconditional range shown in Item (1-1).

[0242] By constituting as in the foregoing, meeting of resins is causedat a portion other than a lens section, because resins flowed in do notarrive the optical functional surface simultaneously. Accordingly, aweld is naturally positioned outside the optical functional surface.

[0243] In the example shown in FIG. 5, thicknesses of the connectingsections are made respectively to be 0.1 mm and 0.2 mm.

[0244] In the example shown in FIG. 6, lengths of the connectingsections are made respectively to be 0.65 mm and 1.3 mm.

[0245] In the example shown in FIG. 7, widths of the connecting sectionsare made respectively to be 0.8 mm and 1.2 mm. Incidentally, theycorrespond respectively to 0.92A and 0.62A, and they satisfy thecondition of Item (1-1).

[0246] Next, as a solution from the aspect of a manufacturing method,there is a method wherein the time to start injecting resins isstaggered as shown in the technology of Item (1-23).

[0247] With respect to resin injection to a metal mold, it is difficultto make each resin inflow speed for each resin inflow port to bedifferent from others, when injection conditions including a meltingtemperature of resins are taken into consideration. Therefore, it ispreferable that the time to start injecting resins is staggered, forcontrolling the meeting timing (meeting position) for both resins.

[0248] When the above-mentioned method is employed, it is possible tocontrol the position of a weld without requiring a substantial costincrease.

[0249] Further, two connecting sections which are different each otherin terms of a shape make it easy to grasp the direction of a lens, whichis an advantage.

EXAMPLE 3

[0250] A general view shown in FIG. 8 represents a diagram of objectivelens 2 in Example 3 that is viewed in the direction of the optical axis,and FIG. 9 is a sectional view of the same objective lens viewed in thedirection shown by the arrow (a), in which the technology of Item (1-14)is employed.

[0251] In the structure of the present example, a lens section isprovided in the form of a floating island at the center of theconnecting section extending in a form of a square as a rectangularshape. The shape thereof is different from those of Examples 1 and 2,and dimensions of the connecting section are also determined based onthe conditions in Item (1-1). Accordingly, there is no problem ofinjection molding. Since connecting sections are extending in almost alldirections from the lens section, handling is more easy, and an area fordata marking and printing is increased, which is an advantage. Further,when the connecting section is made to hit, it is easy to position bothin x direction and y direction on the plane that is perpendicular to theoptical axis, which is an advantage.

[0252] In the present example, a lens section is 0.85 mm, and a lengthof one side of the rectangular connecting section in the form of asquare is 1.3 mm (1.53A), which satisfy the conditions in Item (1-1).

[0253] Though no flange is provided on the lens section, it is alsopossible to provide the flange.

[0254] Though a plastic lens is used in the same way as in Examples 1and 2, a glass mold lens made through compression molding may also beused. In particular, the shape is suitable for compression molding,because of the shape wherein connecting sections are extending from thewhole circumference of the lens section.

[0255] Further, the connecting section is in a shape of a square in theexample shown in FIG. 8, but it is also possible to chamfer or to roundthe corner of the connecting section at need. If the extent ofchamfering is made to be different depending on each corner, this may beutilized for adjusting the lens direction. Even when the rectangle ischanged, as occasion demands, to a shape of a rectangle, a shape of atrapezoid, a shape of a parallelogram and a five-or-more-corneredrectangular shape, these shapes are naturally within a scope of theinvention.

[0256] Incidentally, in the case of an asymmetric shape, an objectivelens can be positioned easily and the direction of the objective lenscan be determined easily.

[0257] When conducting injection molding for this lens, resins are alsomade to flow in through a part of the connecting section, and in thiscase, two or more inflow ports may be provided without sticking to oneinflow port, as occasion demands, and it is also possible to change athickness of the connecting section depending on its location.

EXAMPLE 4

[0258] An objective lens in Example 4 is exactly the same in terms ofshape as those in FIGS. 1-9, and it is a glass lens obtained by heatinga glass pre-form representing a material and then bycompression-molding, in which technologies in Items (1-17) and (1-21)are used.

[0259] Since this is a glass lens, it is excellent in opticalcharacteristics, and it is excellent also in temperature characteristicscompared with a plastic lens.

[0260] Even in this lens manufactured through compression molding, it isnecessary to satisfy the conditions in Item (1-1).

[0261] Namely, it is necessary that the pre-form is subjected tocompression molding so that a lens section may have sufficient opticalfunctions and a connecting section may be formed. If the width of theconnecting section is out of the range of Item (1-1), there is caused aproblem that no connecting section is formed, or molding troubles aregenerated in a lens section in an extreme occasion.

[0262] Therefore, even when a small-sized lens is made with glassmaterial through compression molding, if the shape of the lens satisfiesthe conditions specified in Item (1-1), excellent molding can be carriedout.

[0263] As stated above, the inventions in Items (1-1) and (1-2) offer anadvantage that handling and incorporating in a pickup device are easy.An advantage that inflow of resins and moldability are excellent is alsooffered. Even in the case of compression molding, an excellent lens isobtained if this condition is satisfied.

[0264] In the invention in Item (1-3), the shape and structure of themetal mold are not complicated, and a resin inflow path can be used as aconstitutional component.

[0265] In the invention of Item (1-4), when the lower limit value of therelational expression described in Item (1-4) is exceeded downward,materials do not flow in smoothly and moldability is worsened. When theupper limit value is exceeded upward, on the other hand, a width of aconnecting section is broadened, resulting in an increase of the timerequired for cutting work of the connecting section and an increase oflens load, which is not preferable from the viewpoint of a thermalstrain.

[0266] In the invention of Item (1-5), each individual lens is cut to bein a circular shape, and it can be subjected to rotary adjustment, andcan be mounted easily.

[0267] In the invention in Item (1-6), there are advantages thathandling property is improved by holding both connecting sections andthat an area where marking and printing can be conducted is increased.

[0268] The inventions in Items (1-7)-(1-10), meeting of resins is causedat a portion other than a lens section, because resins flowed in do notarrive the optical functional surface simultaneously. Accordingly, aweld can naturally be positioned outside the optical functional surface.

[0269] In the invention in Item (1-11), since connecting sections areextending in almost all directions from the lens section, handling ismore easy, and an area for data marking and printing is increased, whichis an advantage. Further, when the connecting section is made to hit, itis easy to position both in x direction and y direction on the planethat is perpendicular to the optical axis, which is an advantage.

[0270] In the case of filling resins through a plurality of injectingports in Item (1-12) and in the case of the inventions in Items (1-11)and (1-12), it is possible to mold surely and at high speed, and torestrain occurrence of a shrinkage cavity. In addition, the timerequired for injection molding can be shortened, which makes a cycletime to be shorter, resulting in improvement of production efficiency.

[0271] Further, two connecting sections which are different each otherin terms of a shape make it easy to grasp the direction of a lens, whichis an advantage.

[0272] In the invention in Item (1-15), a weld is located outside anoptical functional surface, which makes it possible to obtain a lenshaving excellent optical characteristics.

[0273] In the invention in Item (1-16), it is possible to obtain a lenshaving excellent optical characteristics.

[0274] In the invention in Item (1-17), it is possible to manufacture alarge number of lenses in the same shape stably and at high speed.

[0275] In the invention in Item (1-18), it is possible to manufacture alarge number of lenses in the same shape stably and at high speed. Sincethe dimensional conditions stipulated in Item (1-1) are satisfied, inparticular, inflow of resins and moldability are excellent, which is anadvantage.

[0276] In the invention in Item (1-19), the shape and structure of themetal mold are not complicated, and a resin inflow path can be used as aconstitutional component.

[0277] In the invention in Item (1-20), it is possible to manufacture alarge number of lenses in the same shape stably and at high speed. Sincethe dimensional conditions stipulated in Item (1-1) are satisfied, inparticular, inflow of resins and moldability are excellent, which is anadvantage.

[0278] In the invention in Item (1-21), it is possible to obtain a lensthat is excellent in temperature characteristics and in transmittance.

[0279] In the invention in Item (1-22), it is possible to give desiredoptical power by a diffractive surface.

[0280] In the invention in Item (1-23), it is possible to control theposition of a weld without requiring a substantial cost increase.

[0281] Next, based on the drawings, there will be explained in detailthe molding process of the invention to which, however, the invention isnot limited.

[0282] The characteristic of the invention is to form integrally aoptical molded component P which is greater in terms of volume andweight than the lens that is incorporated finally in the optical pickupunit, in advance, then, to handle the molded component in the handlingprocess by holding its portion other than the lens as a referenceposition, and to cut the portion other than the lens after incorporatingthe molded component in the optical pickup unit or in the containingcartridge.

[0283] The symbol 0 shown in FIG. 10 represents a schematic view of apart of a metal mold M that is used for molding an optical moldedcomponent P relating to the invention. The metal mold has a resin inflowpath which is mostly H-shaped, and it is the so-called multi-cavitymetal mold (8-cavity, in this case) wherein melted plastic resin flowsin the large diameter path section located at the center, in thedirection perpendicular to the page, and 8 pieces of optical moldedcomponents in total are formed in a single metal mold. As is knowncommonly, the metal mold is composed of a fixed side and a movable side,and these sides are closed when resin flows in, and are parted to openthe inside of the metal mold when the resin is cooled after flowing inand molding is completed, so that the molded component may be taken out.

[0284]FIG. 11 is a sectional view of a certain molding site (includingthe fixed side and movable side) that is viewed in the direction 1 inthe metal mold. The numeral 31 represents a runner that is the firstresin inflow path, 32 represents a gate that is the second resin inflowpath and 33 represents an optical functional section molding section. Asection of the first resin inflow path is circular and a section of thesecond resin inflow path is rectangular.

[0285] As is known commonly, an inner surface of the metal mold, namely,the molding surface has surface finish conducted by any of various typesof processing methods. The optical functional section molding section,in particular, can be structured so that not only an aspheric surfacebut also diffractive ring-shaped zones, phase-shifted ring-shaped zonesand optical path difference provided ring-shaped zones may be formed,and in that case, a cutting tool having an extremely sharp edge is usedto machine the metal mold. As a material for the metal mold, appropriatematerials including plated iron can be selected.

[0286] Though a section of the first resin inflow path (runner) iscircular and has a uniform diameter in the drawing, a diameter and ashape of this runner section do not always need to be uniform. Withrespect to a cross-sectional area and a shape, a diameter, for example,may either be changed from 6 to 4 discontinuously or be changed from 6to 4 continuously to become a tapered shape. Further, a shape of asection may suffer a change such as a change from a circle to arectangle.

[0287] Then, the melted resin flows in the second resin inflow path 32from the first resin inflow path 31, and further flows in the opticalfunctional section molding section 33 through the second resin inflowpath 32, and is cooled, thus, molding is completed and the metal mold isopened.

[0288] In this example of the metal mold, the inflow direction of theresin is linear for both the first resin inflow path and the secondresin inflow path, and both directions agree with each other.

[0289] However, the aforementioned structure may be changed to complywith the total structure of the metal mold and with other circumstances.For example, it is possible to make the first resin inflow path to havea prescribed curve. Further, it is possible to make the resin inflowdirection of the first resin inflow path and that of the second resininflow path to be linear, and further to make them to be in thepositional relationship to cross at right angles. Under this condition,a metal mold takes a three-dimensional shape, resulting in an advantagethat the number of cavities is increased. For example, a shape of themolded component that is molded by the use of the metal mold mentionedabove is one shown in FIG. 20.

[0290] An optical molded component P formed by metal mold M shown inFIG. 10 is formed to be in a shape shown in FIG. 10.

[0291] With respect to each section formed by metal mold M in this case,a diameter of supporting shaft section 41 is 5 mm, a shape of a sectionof connecting section 42 is a rectangle whose one side is 0.5-1 mm and adiameter of optical functional section 43 is 1 mm -1.5 mm.

[0292] Therefore, it is extremely difficult to handle by holdingdirectly the optical functional section 3 that represents a lens site.However, it is easy to hold supporting shaft section 41 that is formedby the first resin inflow path 31 (runner) by handling it as areference, and other operations can be conducted satisfactorily.

[0293] To be concrete, the supporting shaft section 1 is handled as areference for various operations, including holding (grasping) andconveyance in the case of taking out the molded component by opening themetal mold, holding (grasping), conveyance, positioning and attaching(or incorporating or assembling) to another member after taking out, andholding (grasping) for cutting.

[0294] The molded component formed by the metal mold 0 is cut at theposition shown by AA′ in FIG. 11.

[0295] Shape P of the optical molded component that has been cut at theposition AA′ is shown in FIG. 12.

[0296] In the figure, the numeral 41 represents a supporting shaftsection formed by the first resin inflow path 31 (runner), 42 representsa connecting section (or a cross linkage section) formed by the secondresin inflow path 32 (gate) and 43 represents an optical functionalsection formed by the optical functional section molding section 33.

[0297] As explained earlier, what is incorporated actually in theequipment such as an optical pickup unit is the optical functionalsection 43 which is extremely small as stated above and is difficult tobe handled individually. Therefore, it is conveyed under the conditionof molded component P wherein it is united solidly with supporting shaftsection 41 and connecting section 42, and it is cut at the position ofthe connecting section 42 immediately before it is incorporated in theoptical pickup unit finally or after being incorporated, so that theoptical functional section 43 may be mounted on the optical pickup unit.It is further possible for the connecting section 42 to be cut after themolded component P has been housed in a cartridge for conveyance.

[0298] Further, when considering a size of supporting shaft section41—optical functional section 43, it is preferable that the supportingshaft section 41 and the connecting section 42 are naturally greater interms of weight than the optical functional section 3 in the moldedcomponent P, for conducting various types of handling stated above.

[0299] It is further preferable that the total weight of supportingshaft section 41 and connecting section 42 is not less than 70% of thewhole weight.

[0300] In other words, an optical molded component mentioned in Item(2-35) is one like molded component P in the state including asupporting shaft section, a connecting section and an optical functionalsection in FIG. 12, for example, and it is not one showing the state ofmolding after the fixed section and the movable section are parted aftercompletion of the molding in the metal mold shown in FIG. 10.

[0301] Incidentally, for making the handling of the optical moldedcomponent after the molding to be more easy, it is possible to improvethe shape of the metal mold by which the molded component P is molded.

[0302]FIG. 13 shows variations of sectional shapes for the first resininflow path 31 (runner) shape. FIG. 13(a) shows a circle, FIG. 13(b)shows a semicircle and FIG. 13(c) shows a trapezoid that is symmetricallaterally. When an asymmetric shape like FIG. 13(b) or FIG. 13(c) isused, it is possible to prevent that supporting shaft section 41 rollsdown when it is placed on the stand. Further, in the case ofregistering, the shape itself serves as an index, which is an advantage.

[0303] It is further possible to employ the shapes of FIG. 13(d) andFIG. 13(e), taking handling property, moldability and stiffness of thefinished molded component into consideration as other factors.

[0304]FIG. 13(d) shows a shape of a section in which a rectangularportion (a trapezoid portion that is symmetric laterally) is provided ona chord of the semicircle. Due to this shape, stiffness is enhanced,rotation can be prevented and positioning can be conducted easily.

[0305]FIG. 13(e) shows a shape of a section in which a plurality oftrapezoids each being symmetric laterally are combined. Due to thisshape, stiffness is enhanced, rotation can be prevented and positioningcan be conducted easily.

[0306] Optical molded component P shown in FIG. 13(f) is one whereinparallel flat portion 41 a that is almost in parallel with a chordsection is formed on a part of an arc section of supporting section 1.Prevention of its rotation is possible, and positioning thereof is easy.Further, by making this parallel flat portion 41 a to be a fixed side ofmetal mold M, and by making the chord section to be a movable side ofthe metal mold M, the optical molded component P can be removed easilyfrom the fixed side after molding by the metal mold M. Due to this,deformation of supporting section 1 caused in the course of removing canbe controlled, and excellent optical molded component P can be obtained.

[0307] Further, it is also possible to provide protruded portion 41 b ina shape which is almost truncated square pyramid (so-called taperedshape) on the parallel flat section 41 a, as shown in FIG. 13(g) andFIG. 21(a). This protruded portion 41 b has a pair of longitudinal sides41 c which face each other in the longitudinal direction of thesupporting section 41 and a pair of lateral sides 41 d which face eachother in the lateral direction. Incidentally, the corner section of theprotruded portion 41 b is chamfered to make the removing from the metalmold M to be excellent.

[0308] This chamfering may either be in a cornered shape or be in arounded shape, but the rounded shape is better on the point ofreleasability. When the structure shown in FIG. 13(g) is employed,action and effect in the case of the structure shown in FIG. 13(f) cannaturally be exhibited, and further, positioning by using the protrudedportion 41 b is possible. Incidentally, protruded portion 41 b may alsobe formed to be in a shape of a rectangular parallelepiped without beingin a shape of almost truncated square pyramid, as shown in FIG. 21(b).

[0309] As shown in FIG. 22, when O represents an intersecting point of astraight line suspended vertically from the side end portion ofconnecting section 42 of a pedestal section of the protruded portion 41b to the parallel flat portion 41 a and the parallel flat portion 41 a,when the metal mold M is opened, there is generated moment whose centeris on O on supporting section 41. Namely, it is preferable that angle θformed between parallel flat portion 41 a and longitudinal side 41 c isnot more than an angle which creates a tangent line of the circle whosecenter is at O and whose radius is (L²+T²)^(1/2), when L represents alength of a pedestal portion of the protruded portion 41 b in thelongitudinal direction and T represents a length of protruded portion of41 b in the direction of its height. Namely, when the angle θ is made tobe 45° or less, the moment generated in the supporting shaft portion 41is reduced, and releasability is improved greatly.

[0310] Incidentally, the smaller the angle θ is, the more thereleasability is improved. In addition, the releasability is furtherimproved if the joint section between the longitudinal side 41 b and theparallel flat portion 41 a is made to have a radius of curvature thatmakes a gentle curve.

[0311] When a semicircular shape like FIG. 13(b) is employed, inparticular, if an arrangement is made so that a normal line on the chordsection of the semicircle may agree with an optical axis on an opticalfunctional surface of optical functional section 43, it is possible toconduct positioning easily in the case of mounting by utilizing thesurface corresponding to the chord section, which results in thehandling that is more convenient.

[0312] When considering the relationship between the optical functionalsection and an optical axis, shapes of FIGS. 13(a)-13(g) can also beapplied, without being limited to the shape of FIG. 13(b). Namely, inthe case of a trapezoidal shape that is symmetric laterally, a line thatis perpendicular to prarallel two sides of the trapezoid has only toagree with an optical axis of the optical functional section.

[0313] Further, as another improvement, it is also possible to provide athree-dimensional distinguishing mark on supporting shaft section 1through molding as shown in FIG. 14. In this case, the first resininflow path 31 (runner) of the metal mold is processed in advance sothat the distinguishing mark may be formed thereon.

[0314] Now, as shown in FIGS. 18(c) and 18(d), index portion 42 a may beprovided on connecting section 42. In this case, gate 2 of the metalmold M has only to be machined in advance so that the index portion 42 amay be formed on connecting section 42.

[0315] In the example shown in FIG. 14, there are formed bar code andletters. A direction, a size and a shape of these distinguishing markcan be established independently.

[0316] Incidentally, although the bar code and the letters are formed onthe supporting section 41 in FIG. 14, the bar code and the letters maybe formed on the connecting section 42.

[0317] Further, the distinguishing mark like this can also include ametal mold number and a cavity number in addition to symbols indicatinga product name and a lot. If these distinguishing marks are included, itis possible to use them when checking and extracting defective productsin the succeeding process.

[0318] Further, as shown in FIGS. 18(c) and 18(d), index portion 42 athat is based on a distance from the center of an optical axis of theoptical functional section 43 may be provided on connecting section 42.FIG. 18(d) shows that the index portion 42 a is formed by cutting intothe connecting section 42, while, FIG. 18(c) shows that the indexportion 42 a is formed to be protruded from the connecting section 42.Further, FIG. 18(d) shows that the index portion 42 a is formed to be ina shape of a straight line that extends in the lateral direction of theconnecting section 42. FIG. 18(c) shows that the index portion 42 a isformed to be a locus of a circle having a prescribed radius whose centeris on the optical axis. Due to this, it is possible to cut based on theindex portion 42 a when cutting the connecting section 42.

[0319] Further, as another improvement, a concave portion or a convexportion may be provided on the supporting shaft section 41 as shown inFIG. 15 and FIG. 16. Even in this case, the first resin inflow path 31(runner) of the metal mold is processed so that these portions may beformed thereon as shown in FIG. 17.

[0320] These concave portions and convex portions can be used as a markfor positioning, a stand for placing and as a jig for fixing. Forexample, a conveyance guide such as a rail is provided, and whenconveying molded component P in a way that it slides on the rail, if theconcave portion and/or convex portion and the rail are in the state ofloose fitting, the molded component P does not come off the rail. Evenin the case of storing the molded component P in a housing containersuch as a cartridge, if the concave or convex portion is in the state offitting with a member on the housing container, a problem of coming offor damage of the molded component in the container can be solved.

[0321] In this case, the convex portion may be formed to be in a shapethat is almost a truncated square pyramid as shown in FIG. 16(g), or ifa corner section of the convex portion is chamfered, friction with arail can be reduced. If the chamfering in this case is in a roundedshape as shown in FIG. 16(g), friction can be reduced greatly, which isextremely advantageous in practical use.

[0322] Further, as another improvement, it is possible to provide astress concentration portion on connecting section 2 as shown in FIG.18, so that the connecting section 2 may be cut easily.

[0323] If there is formed a V-shaped concave portion that is concave inthe direction that is almost perpendicular to an optical axis on anoptical functional surface of optical functional section 43, as shown inFIG. 18(a), it is possible to cut connecting section 42 only by tiltingsupporting shaft section 41 in the direction of the optical axis afterincorporating the molded component P in an equipment such as an opticalpickup unit. It is also possible to provide a V-shaped concave portionthat is concave in the direction which is mostly the same as an opticalaxis on the optical functional surface of the optical functional section43, as shown in FIG. 18(b).

[0324] Though it is possible to provide the stress concentration portionof this kind by arranging some device on the metal mold, in the same wayas in the aforementioned case, there is sometimes caused a problembecause a cross-sectional area of the path through which the resinpasses becomes small in the second resin inflow path 32. It is thereforepossible to form a stress concentration portion of this kind throughhalf-cutting or stamping after completion of molding.

[0325] Though there has been explained a technology to make handlingafter molding to be easy by improving mainly a metal mold, it is alsopossible to devise the handling in the state of molded component P,after molding.

[0326] For example, in the example shown in FIG. 14, a distinguishingmark is provided on supporting shaft section 41 by devising a shape ofthe first resin inflow path 31, in which, however, a problem thatinformation to be given in the course of molding is fixed is caused.

[0327] After molding, therefore, some pieces of information can begiven. Recording of information of this kind is also an embodiment ofwhat is called “handling” in the invention.

[0328] As an example therefore, there is given an occasion wherein thefirst resin inflow path 31 is processed to provide an informationrecording site as shown in FIG. 19. In this case, it is preferable thatan area representing a rough surface is formed so that an operation togive information and a position to give information may bedistinguished. Incidentally, by processing the gate section 31, theinformation may be provided on the connecting section 42.

[0329] A method to give information includes, for example, stamping,printing and pasting of a label. When simplicity and cost are taken intoconsideration, in particular, printing of an ink jet system ispreferable. It is also possible to combine stamping, printing andpasting of a label appropriately for using them.

[0330] Further, as information to be given or to be recorded, it ispossible to include also a metal mold number and a cavity number inaddition to symbols indicating a product name and a lot. If thesedistinguishing marks are included, it is possible to use them whenchecking and extracting defective products in the succeeding process.

[0331] In the case of printing and label pasting, classification bycoloring can also increase an amount of information.

[0332] As stated above, in the invention of Item (2-1) and Item (2-2),it is possible to hold stably because weight of the portion other thanthe optical functional section is greater than that of the opticalfunctional section.

[0333] In the invention of Item (2-3), Item (2-4), Item (2-35)-Item(2-38), information is recorded on the supporting shaft section which islarger than the optical functional section, therefore, various pieces ofinformation can be held as a molded component even in the case of asmall-sized optical functional section. If the recorded information is ametal mold number, it is possible to trace the relationship between themolded component and the metal mold that has molded the moldedcomponent. If the recorded information is a cavity number, it ispossible to trace about the molded component, retroacting to the momentof molding operations.

[0334] In the invention of Item (2-5) and Item (2-51), a resincirculation path can be manufactured easily, because a supporting shaftsection is formed so that a shape of its section may be circular.

[0335] In the invention of Item (2-6) and Item (2-52), there can beformed a molded component that is stable when it is placed, because asection of the supporting shaft section is formed to be almosttrapezoidal.

[0336] In the invention of Item (2-7) to (2-10) and Item (2-53), therecan be formed a molded component that is stable when it is placed,because a section of the supporting shaft section is formed to be almostsemicircular.

[0337] In the invention of Item (2-11) and Item (2-54), a metal mold canbe designed easily, and positioning is easy.

[0338] In the invention of Item (2-12) to (2-14) and Item (2-55),holding and conveyance of a molded component are easy because the convexportion is formed on the supporting shaft section.

[0339] In the invention of Item (2-15) and Item (2-56), holding andconveyance of a molded component are easy because the concave portion isformed on the supporting shaft section.

[0340] In the invention of Item (2-16) and Item (2-57), cutting is easybecause the stress-concentration portion is formed.

[0341] In the invention of Item (2-17), it is possible to conductcutting easily by tilting the supporting shaft section from the opticalaxis.

[0342] In the invention of Item (2-18), it is possible to conductcutting easily by tilting the supporting shaft section from the opticalfunctional section without moving it in the optical axis.

[0343] In the invention of Item (2-19) to Item (2-23), information isrecorded on the connecting section, therefore, various pieces ofinformation can be held as an optical molded component even in the caseof a small-sized optical functional section. If the recorded informationis a metal mold number, it is possible to trace the relationship betweenthe molded component and the metal mold that has molded the moldedcomponent. If the recorded information is a cavity number, it ispossible to trace about the molded component, retroacting to the momentof molding operations.

[0344] In the inventions of Item (2-24)-Item (2-26), even a lens whichis extremely small in size can be conveyed and positioned in the processeasily, and it can further be incorporated easily in a pickup unit, whenthe lens is handled with a reference represented by a supporting shaftsection provided solidly with the lens, which is an advantage.

[0345] In the invention of Item (2-27), a prescribed position serves asreference and it does not have an influence on the optical functionalsection, thereby, operations can be equalized.

[0346] In the invention of Item (2-28), positioning is conducted byusing the supporting shaft section which is larger than the opticalfunctional section, thereby, positioning can be conducted accurately.

[0347] In the invention of Item (2-29), the supporting shaft sectionwhich is larger than the optical functional section is held (gripped),thereby, holding is easy.

[0348] In the invention of Item (2-30), assembling is conducted by usingthe supporting shaft section which is larger than the optical functionalsection, thereby, mounting and assembling can be conducted surely.

[0349] In the invention of Item (2-31), cutting is conducted withreference of the supporting shaft section which is larger than theoptical functional section, thereby, holding and gripping are sure, anderroneous cutting is prevented.

[0350] In the invention of Item (2-32) to Item (2-34), assembling isconducted by using the supporting shaft section which is larger than theoptical functional section, and cutting is conducted with reference ofthe supporting shaft section which is larger than the optical functionalsection, thereby, the extremely small lens can be incorporated in thedevice easily.

[0351] In the invention of Item (2-39), recording of information isconducted through the method of stamping, and therefore, information canbe given freely as occasion demands after molding, and information isnot separated from the molded component because information is recordedintegrally.

[0352] In the invention of Item (2-40), recording of information isconducted through the method of printing, and therefore, information canbe given freely as occasion demands after molding, and information isnot separated from the molded component because information is recordedintegrally. If information is given through an ink jet system, inparticular, an amount of information can be increased by classificationby coloring.

[0353] In the invention of Item (2-41), recording of information isconducted through the method of label pasting, and therefore,information can be given freely as occasion demands after molding, andan amount of information can be increased by classification by coloring.

[0354] In the invention of Item (2-42), the positioning for the opticalmolded component can be done easily, therefore, it is very advantageousfor the actual use of it.

[0355] In the invention of Item (2-43), the optical molded component canbe surly guided in a production line in a factory, therefore, it is veryadvantageous for the actual use of it.

[0356] In the invention of Items (2-44), (2-58) and (2-59), a supportingshaft section, a connecting section and a molded component having anoptical functional section can be formed easily.

[0357] In the invention of Item (2-45), handling after molding is easybecause a three-dimensional distinguishing mark is formed simultaneouslyin the course of molding.

[0358] In the invention of Item (2-46), a resin flow is excellentbecause the direction of resin inflow is linear.

[0359] In the invention of Item (2-47), a resin flow is excellentbecause the direction of resin inflow is linear continuously.

[0360] In the invention of Item (2-48), a metal mold can be structuredin three dimensions, because a resin inflow path is provided to cross atright angles.

[0361] In the invention of Item (2-49) and Item (2-50), it can beapplied to a mold having a runner or a gate, therefore, it is veryadvantageous for the actual use of it.

[0362] In the invention of Item (2-60) and Item (2-64), assembling theoptical molded component onto a unit can be done easily, therefore, themanufacturing cost, of course, can be reduced. Further, the accuracy inthe assembling each component onto the entire unit can be enhanced.

What is claimed is:
 1. An objective lens for use in an optical pickupapparatus for conducting recording and/or reproducing information for anoptical information recording medium, comprising: a lens section shapedin an approximate circle and including a flange section; and aconnecting section integrally provided to the lens section; wherein thefollowing conditional formulas are satisfied: 0.5≦A≦2.0 0.3A≦B≦1.7A where A is a diameter of the lens section when the lens section isviewed from an direction of an optical axis, and B is a width of theconnecting section when the connecting section is viewed from thedirection of the optical axis.
 2. The objective lens of claim 1, whereinthe connecting section is extended from the lens section in a directionsubstantially perpendicular to the optical axis.
 3. The objective lensof claim 2, wherein the following conditional formulas are satisfied:0.3A≦B≦0.8A
 4. The objective lens of claim 1, further comprising asecond connecting section integrally provided to the lens section,wherein the connecting section and the second connecting section areextended from the lens section in respective opposite directions eachsubstantially perpendicular to the optical axis.
 5. The objective lensof claim 4, wherein the size of the connecting section is different fromthat of the second connecting section.
 6. The objective lens of claim 5,wherein the thickness of the connecting section in the direction of theoptical axis is different from that of the second connecting section. 7.The objective lens of claim 4, wherein the length of the connectingsection in the direction perpendicular to the optical axis is differentfrom that of the second connecting section.
 8. The objective lens ofclaim 5, wherein the width of the connecting section when the connectingis viewed from the optical axis is different from that of the secondconnecting section.
 9. The objective lens of claim 1, wherein theconnecting is shaped in a square and the lens section is positioned atthe center of the square.
 10. The objective lens of claim 1, wherein thelens section is an aspheric lens section.
 11. The objective lens ofclaim 1, wherein the lens section is provided with a diffractivestructure.
 12. The objective lens of claim 1, wherein the objective lensis made of a plastic.
 13. The objective lens of claim 1, wherein theobjective lens is made of a glass.
 14. The objective lens of claim 1,wherein the objective lens is a molded lens with a resin.
 15. Theobjective lens of claim 14, wherein the resin is filled through a singlegate in a mold so that the molded lens has a single connecting section.16. The objective lens of claim 15, wherein the connecting section isused as a resin flowing passage in a mold.
 17. The objective lens ofclaim 14, wherein the resin is filled through plural gates in a mold sothat the molded lens has plural connecting sections.
 18. The objectivelens of claim 14, wherein the resin is filled through two opposite gatesin a mold so that the molded lens has two opposite connecting sections.19. The objective lens of claim 14, wherein the molded lens has a squareconnecting section and the resin is filled through one end of the squareconnecting section.
 20. The objective lens of claim 14, wherein themolded lens has a weld portion at a position other than an opticalfunctional section.
 21. The objective lens of claim 14, wherein themolded lens is produced by a method of injection molding.
 22. Theobjective lens of claim 14, wherein the molded lens is produced by amethod of compression molding.
 23. A molded optical component,comprising: a supporting shaft section having a first cross-sectionalarea; a connecting section integrally provided to the supporting shaftsection and extended in an axial direction of the supporting shaftsection, and the connecting section having a second cross-sectional areasmaller than the first cross sectional area; and an optical functionalsection integrally provided to the connecting section.
 24. The moldedoptical component of claim 23, wherein the sum weight of the supportingshaft section and the connecting section is greater than the weight ofthe optical functional section.
 25. The molded optical component ofclaim 23, wherein the sum weight of the supporting shaft section and theconnecting section is 70% or more of the total weight of the moldedoptical component.
 26. The molded optical component of claim 23, furthercomprising: an information recording section provided on the supportingshaft section.
 27. The molded optical component of claim 23, furthercomprising: an information recording section provided on the connectingsection.
 28. The molded optical component of claim 23, wherein thesectional form of the supporting shaft section is shaped in almost acircle.
 29. The molded optical component of claim 23, wherein thesectional form of the supporting shaft section is shaped in almost atrapezoid.
 30. The molded optical component of claim 23, wherein thesectional form of the supporting shaft section is shaped in almost asemicircle.
 31. The molded optical component of claim 30, wherein aparallel flat portion that is almost in parallel with a chord section ofthe semicircle is formed on a part of an arc section of the semicircleof the supporting section.
 32. The molded optical component of claim 31,wherein a protruded portion that is protruded from the parallel flatportion and is shaped in almost a truncated square pyramid is formed onthe parallel flat portion.
 33. The molded optical component of claim 32,wherein the protruded portion has four side sections comprising a pairof longitudinal sides which face each other in the longitudinaldirection of the supporting shaft section and a pair of lateral sideswhich face each other in the lateral direction, and wherein an angleformed between the longitudinal side and the parallel flat section ismade to be 45° or less.
 34. The molded optical component of claim 30,wherein a normal line on a chord section of the semicircle almost agreeswith an optical axis on an optical functional surface of the opticalfunctional section.
 35. The molded optical component of claim 23,wherein a protruded portion is formed on the supporting shaft section.36. The molded optical component of claim 35, wherein the protrudedportion is shaped in a truncated square pyramid.
 37. The molded opticalcomponent of claim 35, wherein a corner section of the protruded portionis chamfered.
 38. The molded optical component of claim 23, wherein aconcave portion is provided on the supporting shaft section.
 39. Themolded optical component of claim 23, wherein a stress-concentrationportion is formed on the connecting section.
 40. The molded opticalcomponent of claim 39, wherein the stress-concentration portion is aV-shaped concave portion shaped in a direction perpendicular to anoptical axis of an optical functional surface of the optical functionalsection.
 41. The molded optical component of claim 39, wherein thestress-concentration portion is a V-shaped concave portion shaped in adirection almost equal to a direction of an optical axis of an opticalfunctional surface of the optical functional section.
 42. The moldedoptical component of claim 23, wherein an index section is provided onthe connecting section on a basis of a distance from a center of theoptical axis of the optical functional section.
 43. The molded opticalcomponent of claim 42, wherein the index section is formed by cutting amark in the connecting section.
 44. The molded optical component ofclaim 42, wherein the index section is formed by protruding a mark fromthe connecting section.
 45. The molded optical component of claim 42,wherein the index section is formed to be a straight line extended alongthe widthwise direction of the connecting section.
 46. The moldedoptical component of claim 42, wherein the index section is formed to bea locus of a circle having a prescribed radius whose center is on theoptical axis.
 47. A method of handling a molded optical component,comprising steps of: molding an optical component by a mold which isprovided with a first resin flow path having a first cross sectionalarea, a second resin flow path which locates in continuation to thefirst resin flow path in a resin flow direction and has a second crosssection area smaller than the first cross sectional area, and an opticalfunctional section forming section which locates in continuation to thesecond resin flow path in a resin flow direction; taking out the moldedoptical component from the mold, wherein the molded optical componentcomprises a supporting shaft section corresponding to the first resinflow path, a connecting section corresponding to the second resin flowpath and an optical functional section corresponding to the opticalfunctional section forming section; and handling the molded opticalcomponent on a basis of the supporting shaft section.
 48. The method ofclaim 47, further comprising: cutting the supporting shaft section ofthe molded optical component.
 49. The method of claim 48, wherein thesupporting shaft section is cut out at a predetermined section.
 50. Themethod of claim 49, wherein the supporting shaft section is cut out soas to have a predetermined length.
 51. The method of claim 47, whereinthe handling step is a step of positioning the molded optical component.52. The method of claim 47, wherein the handling step is a step ofholding the molded optical component.
 53. The method of claim 47,wherein the handling step is a step of mounting the molded opticalcomponent.
 54. The method of claim 47, wherein the handling step is astep of cutting the molded optical component.
 55. The method of claim47, wherein the handling step comprises a stem of assembling the moldedoptical component with another member and thereafter a step of cuttingthe connecting section.
 56. The method of claim 55, wherein the anothermember is a cartridge for conveyance.
 57. The method of claim 55,wherein the another member is an optical pickup unit.
 58. The method ofclaim 47, wherein the handling step is a step of recording informationon the supporting shaft section.
 59. The method of claim 47, wherein thehandling step is a step of recording information on the connectingsection.
 60. The method of claim 58, wherein the information is areference number of a mold.
 61. The method of claim 58, wherein theinformation is a reference number of a cavity.
 62. The method of claim58, wherein the step of recording information is conducted by marking.63. The method of claim 58, wherein the step of recording information isconducted by printing.
 64. The method of claim 58, wherein the step ofrecording information is conducted by pasting.
 65. The method of claim47, wherein the first resin flow path is adapted to provide a protrudedportion or a concave portion on the supporting shaft section, theprotruded portion or the concave portion is used as a guide forpositioning.
 66. The method of claim 47, wherein the first resin flowpath is adapted to provide a protruded portion or a concave portion onthe supporting shaft section, the protruded portion or the concaveportion is used as a guide for handling.
 67. A mold for producing asoptical component, comprising: a first resin flow path having a firstcross sectional area; a second resin flow path which locates incontinuation to the first resin flow path in a resin flow direction andhas a second cross section area smaller than the first cross sectionalarea; and an optical functional section forming section which locates incontinuation to the second resin flow path in a resin flow direction;wherein the molded optical component comprises a supporting shaftsection corresponding to the first resin flow path, a connecting sectioncorresponding to the second resin flow path and an optical functionalsection corresponding to the optical functional section forming section.68. The mold of claim 67, wherein the first resin flow path is shaped tohave a portion to form a three-dimensional distinguishing mark on thesupporting shaft section.
 69. The mold of claim 67, wherein a flowdirection of a resin through the first resin flow path and the secondresin flow path is almost a straight line.
 70. The mold of claim 67,wherein a flow direction of a resin on the first resin flow pathconforms with that on the second resin flow path and is almost astraight line.
 71. The mold of claim 67, wherein a flow direction of aresin on the first resin flow path is perpendicular to that on thesecond resin flow path.
 72. The mold of claim 67, wherein the firstresin flow path is a runner.
 73. The mold of claim 67, wherein the firstresin flow path is a gate.
 74. The mold of claim 67, wherein the firstresin flow path is shaped such that the cross sectional form of thesupporting shaft section becomes almost a circle.
 75. The mold of claim67, wherein the first resin flow path is shaped such that the crosssectional form of the supporting shaft section becomes almost atrapezoid.
 76. The mold of claim 67, wherein the first resin flow pathis shaped such that the cross sectional form of the supporting shaftsection becomes almost a semicircle.
 77. The mold of claim 67, whereinthe first resin flow path and the optical component forming section areshaped such that a normal line on a chord section of the semicirclealmost agrees with an optical axis on an optical functional surface ofthe optical functional section.
 78. The mold of claim 67, wherein thefirst resin flow path is shaped such that a protruded portion is formedon the supporting shaft section.
 79. The mold of claim 67, wherein thefirst resin flow path is shaped such that a concave portion is formed onthe supporting shaft section.
 80. The mold of claim 67, wherein thesecond resin flow path is shaped such that a stress-concentrationportion is formed on the connecting section.
 81. A method of molding anoptical component with a mold described in claim
 67. 82. A method ofmolding an optical component with a mold having plural gates for acavity corresponding to the optical component, comprising: filling resininto the cavity thorough the plural gates, wherein a timing to startfilling the resin is different for each of the plural gates.
 83. Anoptical pickup apparatus, comprising: the objective lens described inclaim
 1. 84. A method of assembling an optical pickup unit, comprisingsteps of: mounting the optical functional section of the molded opticalcomponent described in claim 23 on an optical pickup apparatus whileholding the supporting shaft section of the molded optical component;and cutting the connecting section.
 85. The method of claim 84, whereinin the cutting step, the connecting section is removed from the lenssection so that the lens section becomes a circle-shaped lens sectionprovided with no portion protruded from the circle-shaped lens section.86. The method of claim 84, wherein the weight of the supporting shaftsection is greater that that of the optical functional section.
 87. Themethod of claim 84, wherein the volume of the supporting shaft sectionis greater that that of the optical functional section.
 88. A method ofassembling a package, comprising steps of: mounting the opticalfunctional section of the molded optical component described in claim 23on a container while holding the supporting shaft section of the moldedoptical component; and cutting the connecting section.
 89. The method ofclaim 88, wherein the weight of the supporting shaft section is greaterthat that of the optical functional section.
 90. The method of claim 88,wherein the volume of the supporting shaft section is greater that thatof the optical functional section.